The present invention relates to systems and methods for anticipating wireless signal loss and more particularly to systems and methods for providing robust location based services based on the anticipated wireless signal loss.
The quality and continuity of wireless service coverage varies greatly between different geographic locations. In a wireless telecommunication system, such as a cellular telephone system, telephone calls are dropped more often than in a conventional wired or wireline system. There are a number of reasons why a telephone call with a wireless telephone may be dropped or lost. One reason for dropped calls is that the wireless telephone has left the coverage area of the wireless system. As is well known, cellular telephone systems are divided into cells, each of which is served by a base station which communicates with wireless telephones (i.e., mobile telephones) located within the cell. The conglomeration of all the cells together make up the coverage area of a certain cellular system/service provider. If a mobile telephone travels outside the coverage area, the wireless communication channel between the mobile telephone and the wireless system will be lost and the call will be dropped. In some situations the mobile telephone may be entering the coverage area of another cellular service provider. In such a case, the call may continue only if the mobile telephone has roaming privileges in that other cellular system.
Another reason that an established call may be dropped in a cellular system is due to handoff. As is well known, when a mobile telephone travels from one cell to another cell, the call is handed off from the base station serving the one cell to the base station serving the other cell. In some situations the base station serving the other cell may not have any radio channels available for communication with the mobile telephone at the time of the handoff. In such a situation the established call with the mobile telephone will be dropped. Another reason for dropped calls in a cellular system is coverage holes or gaps, which are areas in the geographic serving area which do not receive signals from the system for some reason. Such coverage holes or gaps include both indoor and outdoor areas. If a mobile telephone enters a coverage hole where coverage is not available, radio communication with the serving base station will be lost and the call will be dropped. Calls in a cellular system may also be dropped due to RF interference, equipment failures and other environmental/structural obstacles which may impede signal establishment within the network.
Whether the wireless device is a telephone, laptop, palmtop or other device, the popularity of these devices is ever increasing. However, as the demand for these devices has exponentially increased, the quality of performance of many of these devices has somewhat suffered. This phenomenon is especially evident with respect to wireless telephones where one telephone from one service provider may have a completely different quality of reception than a telephone from another service provider in the same exact physical location. The brochures and information provided by wireless service providers thus only give general maps and locations as to their “reach” or coverage of service. However, as most people, especially those who commute back and forth between two fixed locations every day and those who may travel in the same general areas, it would be helpful to know beforehand, which service providers offer the best service in those predefined areas. For example, in large cities, reception quality can vary greatly due to the great amount of interference in those areas.
Accordingly, in view of the above it would be extremely desirable to be able to anticipate wireless signal loss and provide robust location based services even in view of an impending or occurring wireless signal loss.